The *real* way to disable text selection

I was recently asked by UX to make the text of my fancy custom dropdown selects unselectable. A lot of silly scripts out there that disable text selection are application-unfriendly. They go beyond unselectable and make the element totally non-interactive. But I still want the dropdown to work when you click it. Solution = css for the "good" browsers, and javascript for internet explorer.

CSS

.unselectable{
    -moz-user-select: none;
    -webkit-user-select: none;
}

JS

if(document.attachEvent){
    function returnFalseFn(){
        return false;
    }
    jQuery('.unselectable').each(function(){
        this.attachEvent('onselectstart', returnFalseFn);
    });
}